1. Field of the Invention
The present invention relates to a slenderized animal fiber that is slenderized by drawing and maintains the resulted state temporarily or permanently, and a method for preparation thereof, and a spun yarn that is obtained by being mixed with said animal fiber.
2. Description of the Prior Art
Conventionally several attempts to apply a drawing treatment to an animal fiber have been made in order to make an bulky or lightweight animal fiber, to improve a heat retaining property and to manufacture a spun yarn of a finer yarn count. In Japanese Patent Publication No. Sho44-15136, a method is disclosed that after a wool top sliver is twisted in accordance with a twisting method of one-plied top sliver, two-plied top sliver and multiplied top sliver, the top sliver is given a drawing of 30% in an aqueous solution of a penetrating agent and a nonion surfactant at 70xc2x0 C., and then the top sliver is drawn and set at 50xc2x0 C. for one hour, and subsequently it is cooled in water and untwisted and dried. Since the object of the above-described processing is to set a state drawn temporarily, the crimps of the wool fibers are recovered by releasing the temporary set in a relaxing process followed.
In Japanese Patent Publication No. Sho46-33141, a method is disclosed that after the wool top slivers, in the case of sliver of 20 g/m, are given approximately 0.05 to 0.4 turns/cm of twist by a twisting method of one-plied top sliver, two-plied top sliver and multi-plied top sliver, the sliver is given a drawing of 30% in water at 100xc2x0 C. and kept setting for approximately one hour in water, or the sliver is given a drawing of 20% in an aqueous solution of 2% of monoethanolamine bisulfite at 80xc2x0 C. and kept setting for 40 minutes, and then the sliver is washed in water, untwisted, air-dried or dried to obtain latent contraction or latent crimps. However, this is not a method for decreasing fiber diameter of wool fiber and increasing fiber length.
In Japanese Patent Laid-Open No. Hei5-500989, a complicated drawing equipment and a drawing method by a false twisting method for forming slenderized wool staple fibers are indicated, and in this document it is described that 50 to 110 g/m of twistless sliver or roving is treated with a wetting agent 0.25 to 1 g/l and that as a plasticizer for producing a mercapto anion in protein fibers, 1 to 75 g/l of sulfite, bisulfite or meta-bisulfite of sodium, ammonium or potassium, an alkali itself, an alkali salt, sodium thioglycolate or ammonium thioglycolate are used. However, formation of a mercapto anion by the above-described method is possible only in an alkali side condition. Therefore, though it describes a drawing of protein fibers under existence of an alkali, a sufficient dipping time and a comparatively high temperature are required in order to make it plasticize. Under the conditions of the dipping time for about several seconds at low temperature, even if a sliver bundle is drawn by 100%, practically by 60%, single fiber breakage occurs and results in drawn sliver containing many short fibers. In the method of this document where in order to plasticize the protein fibers of the twistless sliver, the sliver is introduced into a dipping bath at the speed of 13.2 m/min, 3 m/min, or 6 m/min, twist factor of approximately 120 or 180 using a false-twist method well used in a spinning process of a synthetic fiber and stretched by 100%, and then reduction set by steam in a residence time of 2 minutes, and subsequently restored to a twistless state to oxidize in a hydrogen peroxide bath, and rinsed and dried, an oxidation/reduction set is given in order to stabilize a permanent set but a neutralization treatment with an acid or an base is not applied. Therefore, since the drawn protein fibers obtained are basic, the fiber has a tendency of yellowing in a following heating treatment.
In Japanese Patent Laid-Open No. Hei7-3556 a following method is disclosed; a twistless sliver of animal fibers of 30 mm or more in fiber length are dipped and treated in hot water of 80xc2x0 C., or in an aqueous solution at 80xc2x0 C. containing 1.0% by weight of thioglycolic acid and 1.5 mols of urea and adjusted to pH 2.5 with 25% of aqueous ammonia solution, or in aqueous solution at 80xc2x0 C. containing 2.0% by weight of thioglycolic acid and 1.5 mols of urea and adjusted to pH 3.7 with 28% of aqueous ammonia solution, and then at first is drawn 1.05 times between six nip rollers respectively using nip rollers of a small diameter. Subsequently the sliver is drawn up to 1.49 times between the six nip rollers and simultaneously a reduction set is given by steaming treatment with a vapor pressure of 2 kg/cm2. In the next process the sliver is oxidized with 1% of hydrogen peroxide in aqueous solution at pH 7, at 40xc2x0 C., for 10 minutes using a top dyeing machine and then washed and dried in a back washer. However, since this method gives a roller drawing to the twistless sliver, it has several problems on processing operation such as especially a fiber wrapping on a roller surface, and slipping-off of a sliver by roller drafting system, a low productivity and a high cost associated with the above-described defect, for example.
In the case of natural wool fibers, their finest has a diameter of 15 to 16 microns. Since such wool fibers have an extremely little quantity of supply and are very expensive, an industrial technology that can supply such wool fibers at low cost has been desired. It is known that when a single fiber of animal fibers, especially wool fibers is fully swelled in water and drawn, it can be drawn up to from 50% to 60%. However, the method for obtaining a slenderized fiber by which the fiber length is increased and the extended state is permanently retained without damage of bilateral structure is not known. The present invention provides the above-described slenderized animal fiber with the properties of less-fiber contraction in boiling water, less solubility of alkali and high solubility of urea-bisulfite (UB) and the like, in addition to above-described properties, and the method for preparation thereof.
The present invention relates to a slenderized crimped animal fibers having a lowering rate of reduction percentage of tensile strength for undyed spun yarn no less than 10% fiber contraction in boiling water of no more than 1%, alkali solubility of no more than 22% by weight and UB solubility of no more than 35% by weight, wherein the slenderized crimped animal fibers are prepared by being drawn by practically 1.20 to 1.60 times after an anisotropic swelling is given to the animal fibers consisting of bilateral structure using basic plasticizing and swelling agents.
And the present invention relates to a method for preparation of the above-described slenderized crimped animal fiber, comprising steps of:
a) a process wherein an actual twist is applied to an animal fiber sliver;
b) a process wherein a twisted animal fiber sliver is swelled and plasticized by a basic aqueous solution and subsequently an anisotropic swelling is given to the animal fiber consisting of a bilateral structure;
c) a reduction process wherein a disulfide bond in the anisotropically swelled and plasticized fiber is cleaved;
d) a drawing process wherein the reduced and anisotropically swelled and plasticized fiber is drawn by practically 1.20 to 1.60 times;
e) a process wherein the drawn animal fiber is oxidized to reproduce a disulfide bond;
f) a process wherein the fiber is neutralized with an acid to be de-swelled;
g) a drying process in an tentionless condition,
wherein the dipping and squeezing is repeated using at least each three pairs of squeezing rollers provided in each of an oxidation treatment bath, a neutralization treatment bath and hot water washing baths installed before and after the preceding two baths respectively and the oxidation treatment is conducted at 15 to 25xc2x0 C.
Further, the present invention relates to a slenderized animal fiber being in a state of temporarily fixed slenderized form with a crimp-recovering property by de-swelling treatment with acid and wet heat treatment, having a lowering rate of reduction percentage of tensile strength for undyed spun yarn of no less than 10%, fiber contraction in boiling water of completely recover level where the fiber subjected to elongation of 1.20 to 1.30 times recovers the original length, an alkali solubility of no more than 15% by weight and a UB solubility of no more than 40% by weight, wherein the slenderized animal fiber is prepared by being drawn by practically 1.20 to 1.30 times after an anisotropic swelling is given to the animal fiber consisting of bilateral structure using basic swelling and plasticizing agents.
Moreover, the present invention relates to a method for preparation of the above-described slenderized animal fiber, comprising steps of:
a) a process wherein an actual twist is applied to an animal fiber sliver;
b) a process wherein a twisted animal fiber sliver is swelled and plasticized by a basic aqueous solution and subsequently an anisotropic swelling is given to the animal fiber consisting of bilateral structure;
c) a reduction process wherein the anisotropically swelled and plasticized fiber is drawn by practically 1.20 to 1.30 times;
d) a process wherein the fiber is neutralized with an acid to be de-swelled;
e) a drying process in a stretched condition,
wherein the dipping and squeezing is repeated using at least each three pairs of squeezing rollers provided in each of a neutralization treatment bath and hot water washing baths installed before and after the preceding two baths respectively and the neutralization treatment is conducted at 15 to 25xc2x0 C.
In more detail the present invention relates to the method for preparation of the above-mentioned slenderized animal fiber, wherein the anisotropic-swelling and plasticization treatments are performed by dipping the twisted animal fiber sliver in a basic aqueous solution of pH 7.6 to 10.5 containing a swelling agent and a plasticization agent for 5 to 40 minutes at 30 to 80xc2x0 C.
In addition, the present invention relates to a method for preparation of a bulky animal fiber spun yarn, wherein the above-described slenderized animal fiber is mixed with un-drawn animal fiber and spun, and then by relaxation, an original length of a temporarily fixed animal fiber is recovered.